Earworm
by skygirl55
Summary: Soulmate Semi-AU set Season 2, Post-Sucker Punch. One-shot.


**Earworm**

Soulmate Semi-AU set Season 2, Post-Sucker Punch. One-shot.

* * *

Sitting at her desk on that gloomy Wednesday morning, Kate Beckett sighed and rested one hand against her cheek, propping her elbow against her desk, and used the other hand to absentmindedly drum her fingertips on the side of her coffee mug. She was attempting to read through several new policy statements issued by the NYPD, but the combination of the dreary morning and the uninteresting verbiage made that task nearly impossible. Giving up for the moment, she leaned back in her seat and placed her fingertips at her temples, giving them a gentle rub. The weather had also provided her with a dull headache, which certainly did not aid in her concentration. Perhaps, she decided, the solution was more coffee.

Kate reached for her cup to finish what remained, but her grip slipped and the mug began to tumble from her grasp. She scrambled for it and managed to catch it before it fully tipped over, but some of the brown liquid did slosh out and land in the area between her keyboard and computer monitor. She cursed under her breath, glad nothing important had been soaked, but annoyed nonetheless.

She did her best to coral the liquid with one of the paper-thin NYPD-issue tissues she had nearby, but they did virtually nothing to soak up the coffee. A quick glance in her top desk drawer told her she had no spare napkins laying around, so she needed to get some from the breakroom.

Just as she stood from her desk, Kate heard the melodic phrase, " _I'm singin' in the rain_ ," float through her mind and she couldn't help but roll her eyes. Of course since it was raining outside her soulmate was singing that song; he was ridiculous like that. Er—not that she believed in soulmates. That was a ludicrous notion that of course was a made-up fairy tale. But if she _did_ believe in soulmates, she doubted she would ever want to meet the man who supposedly belonged to her. Based on the songs he sang, he was probably quite a handful.

Ever since Kate was a little girl, she'd heard the same fairy tale. Yes, there was Cinderella, Sleeping Beauty, and all the other classics, but this tale was one grounded much firmly in reality, though still, in her mind, fantastical. Her parents, grandparents, aunt, and uncle told her about the songs she mysteriously had playing in her head. Not the song she'd hear on the radio and perhaps sing to herself and hour or two later, but the bolt-from-the-blue, 'where did that come from?' songs that randomly played in her mind. For these songs, there was one simple (albeit difficult to believe) explanation: these were the songs her soulmate was singing aloud.

Soulmates, they told her, were connected through their minds and hearts, so that when one of them sang aloud, the other heard the song in his or her head. In that way they were tethered long before they ever met and, at least in theory, that connection would help them find each other one day.

Ever the skeptical child, Kate remained quite doubtful of such a phenomenon, even when she began to hear random songs in her head around the age of sixteen. She knew none of her relatives had found their soulmates (naturally, she had asked) and at that point was not aware of any other couples that had matched up. Thus, to her, the idea that the earworms she had were actually being sung by her soulmate seemed as crazy as a fairy godmother with a magic wand appearing before her to grant her a wish.

In fact, Kate only ever acknowledged the potential soulmate on the other end of the songs when whatever song playing in her mind annoyed her—which, actually, was quite often. Nothing was more irritating than trying to focus on an important case only to have Bon Jovi start blasting through her skull. Or, worse, Britney Spears. To his credit, he did have a mostly varied taste (assuming he existed at all). In any given week she could hear showtunes, classic rock, and sometimes even a little bit of country. The only genre he stayed away from was rap, for which she had no complaints. She also suspected he may have been a father or in charge of a younger sibling, because there had been a heavy period of lullabies in her teens, right around the time she first started hearing the songs.

Whatever the reason for the songs in her head, Kate didn't think about it too frequently. Mostly, they just became background noise. Unless, of course, she was already annoyed or on edge, like she was that morning; then she was likely to punch her soulmate—if he existed at all.

After grabbing a small chunk of napkins from the breakroom supply, Kate began walking back towards her desk when she heard _Singin' in the Rain_ being sung. She stopped walking in the middle of the hall when she realized the song was not only inside her head, but out. Someone was in the Twelfth singing the exact part of the song playing in her head. That…seemed unlikely.

She took a step towards the elevators, where she thought she heard the sound coming from, but before she could move any further, a man rounded the corner singing, "… _and dancing in the_ —oh! Morning Beckett!"

Kate froze. She blinked, and stared, and blinked again, absolutely in shock—shock! Richard Castle was singing the song playing in her head, but surely… "No…" she rasped out, a mixture of confused and possibly a little bit nauseated.

"No? What's no? Are you okay Beckett? You're looking a little pale."

His genuinely concerned tone was flattering, but not something she could focus on in that moment; her mind was spinning. "You…you're singing _Singin' in the Rain…_ "

"Well, sure, it's raining outside so…" His voice drifted off and his brow wrinkled slightly. "Why? Did you…oh my gosh Beckett-"

"No!" she said while his expression morphed from confused to excited, but her comment did nothing to stop him.

"-did you hear _Singin' in the Rain_ in your head before I got here?"

"I-I…um…"

"Beckett!" He practically squealed with glee as he rushed over and grabbed onto her arms with his hands. "This is amazing! We have to try it out!"

"Wha…I…" Though she was annoyed with herself for only being able to stammer, Kate simply could not form a coherent word.

Castle—Richard Castle! He was the man whose ludicrous songs she'd been subject to for fifteen years! Well…actually, that did make sense. Castle was a father, as she'd guessed, and he _was_ a handful, but…but…how could this be real? How could they be cosmically connected? How could she—god—be destined to spend the rest of her life with him? Yes, just a few weeks earlier, after Dick Coonan had shown up in her life and turned everything upside-down, she had admitted that she wanted him around and she did stick by that statement. He was entertaining, and kind, and…okay, maybe not bad on the eyes, but for forever? Forever with Castle? How was she supposed to wrap her mind around that?

"Beckett please—c'mon we have to know for sure. I—I know!" he clapped his hands together and then gently spun her around. "Go back in the breakroom and sing something to yourself. I'll wait out here, and then we can see if what I hear is what you sing, okay?"

Too in a daze to argue to the contrary, Kate turned and shuffled her way back into the breakroom, still clutching the napkins in her hand. Once the door swung shut behind her, she stood frozen a foot away from the coffee pots.

What the hell was she supposed to sing?

* * *

Castle paced back and forth in a tight line in front of the breakroom. Beckett had been in the room for at leas a minute and a half yet he heard no songs in his head, so what was she doing in there? The anticipation was killing him!

As he paced, Castle thought with amazement that he'd finally found her—his soulmate—and she'd been right there in front of him for the prior almost two years!

Practically from the moment they met, Castle had a crush on Kate Beckett; he would never deny that factor. Now, after getting to know her little by little, that crush had blossomed into some level of romantic feelings. He cared for her and found her to be an incredible person. Were they to become more intimately acquainted, he was certain falling in love with her would not be difficult—and that was even before he knew about their soulmate status. As soon as they were able to confirm they were in fact soulmates…well, there'd be no stopping them; they would be extraordinary.

Finally, after two full minutes of waiting, Castle heard a faint melody inside his head. It was very soft and tentative, but he could still hear it. The song was _Twinkle, Twinkle Little Star_. Castle's brow wrinkled for a moment, thinking that song a peculiar choice, but he was too anxious to question it, so he blasted into the breakroom to find Kate several feet away, her back turned towards the door. He swept his eyes across the room confirming they were alone before letting the door shut behind him and stepping forward.

"Why'd you choose _Twinkle, Twinkle Little Star_?"

She snuffled. "I could think of anything else."

Castle's heart fluttered, but not because she confirmed their soulmate status, but because she sounded as though she was crying, and he immediately felt concerned; Kate Beckett was not a crier—at least, not to his knowledge. "Whoa hey—don't cry; don't be upset." He stepped up beside her and placed a gentle hand on his shoulder. "You're…are you upset Beckett?"

She turned to him, brushing tears from beneath her eyes. "I…I don't know what I am. Surprised, I guess."

"That's fair. I didn't really see this coming either. This morning, I mean. I've always thought you were extraordinary, but I think you know that already." He gave her a dopey smile, hoping she'd smile in return, but instead she merely stared and looked uncertain, so he gave her arm a little rub. "Hey, c'mon; talk to me."

She shrugged and used one of the napkins in her fist as a tissue. "I kind of thought it was an old wives tale—hearing the songs in your head that someone else sang."

"Really? You never met any couples?"

She shook her head. "Can't think of any."

Castle hummed as he considered her comment. He'd definitely read about couples who had found their soulmates in the way they had, but he couldn't think of any that he knew personally. In his mind, that only made them more incredible. "Well, I think it's awesome. Like a little secret way of talking to each other when we're apart!"

She groaned. "Oh great so now you're just going to randomly break out into song."

"Don't be annoyed—I'd only do it if you weren't around."

"Right…"

As her tone sounded more like a huff than anything else, he gently brushed the side of his index finger along the edge of her jaw. "You okay? This doesn't have to change anything, you know. Not right away, I mean. If you want us to still be just partners or try to get to know each other better as friends—that's fine with me, but just know: I'm not going anywhere."

She gazed at him steadily for a moment, almost challenging him to back down on his decision, but he never did, so she stepped a bit closer to him and landed her hands at his waist. "I don't want you to."

Slipping his arms around her shoulders with ease, he hummed out, "Good." With he that close to him, Castle felt the sudden urge to kiss her, but he knew he had to restrain himself. Sharing their first kiss in the breakroom at the Twelfth would not have felt entirely out of place considering that they had got to know each other through well through Kate's work. However, his concern was that their moment would be interrupted by any one of her coworkers, and he most certainly did not want that, so he settled for pressing his lips against the top of her head and holding her close until she began to slide away.

She gave him a borderline shy look that had his heart fluttering all over again before she moved towards the breakroom exit. She'd only taken one step before she turned back around to face him and spoke his name.

"Yeah?"

"One question about the songs: why so much Disney?"

He gave a simple shrug. "Well, I do have a young daughter."

She placed her right hand at her hip and gazed at him with one eyebrow raised. "I'm talking about two weeks ago when you sang every song from _Mulan._ "

"That's a great movie!"

She let out a light laugh. "I'm not saying it's bad."

Shrugging, he said, "Well I'll try to keep Disney to a minimum. Do you have suggestions? Radio-Castle will accept requests."

Kate rolled her eyes at his grin. "You're ridiculous."

"And," he countered, stepping up and giving her arm a playful nudge, "you could probably sing a little bit more in your life." It really was quite disappointing. She hardly sang more than once a week. He figured he'd never find his mate at that rate, so he was endlessly grateful she had been the one to figure it out.

She nipped at her bottom lip with her tongue before nodding. "I'll…think about it."

He leaned forward and wiggled his eyebrows at her. "Don't you worry, Beckett; It's gonna be great."

* * *

 **A/N:** This prompt was from Tumblr - "What if you were just at a restaurant one day and you started randomly singing because your soulmate was singing int he shower/ omfg! what if this is why you get a song stuck in your head - because your soulmate is singing it somewhere" [users the-vashta-nerada & kauthecat]

Thanks for reading!


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